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            <h1 style="display: none">vuex中辅助函数</h1>
            
            <div class="markdown-body">
              <p><span>在正规的公司开发中很少用:</span></p>
<p>this.$store.commit(“xxx”),this.$store.dispatch(“xxx”),this.$store.state.xxx,因为这样显得十分累赘，所以此时就推荐用辅助函数来替代。</p>
<p>以下三个例子都公用一个store.js</p>
<div class="code-wrapper"><pre><code class="hljs javascript"><span class="hljs-keyword">import</span> Vue <span class="hljs-keyword">from</span> <span class="hljs-string">&#x27;vue&#x27;</span>
<span class="hljs-keyword">import</span> Vuex <span class="hljs-keyword">from</span> <span class="hljs-string">&#x27;vuex&#x27;</span>
<span class="hljs-keyword">import</span> axios <span class="hljs-keyword">from</span> <span class="hljs-string">&quot;axios&quot;</span>

Vue.use(Vuex)

<span class="hljs-keyword">export</span> <span class="hljs-keyword">default</span> <span class="hljs-keyword">new</span> Vuex.Store(&#123;
  <span class="hljs-attr">state</span>: &#123;
    <span class="hljs-attr">uname</span>:<span class="hljs-string">&quot;&quot;</span>
  &#125;,
  <span class="hljs-attr">mutations</span>: &#123; <span class="hljs-comment">//专门负责修改state中的变量</span>
    <span class="hljs-function"><span class="hljs-title">setUname</span>(<span class="hljs-params">state,uname</span>)</span>&#123;
      state.uname=uname;
    &#125;
  &#125;,
  <span class="hljs-attr">actions</span>: &#123; <span class="hljs-comment">//专门负责发送异步ajax请求，从服务器端获取数据</span>
    <span class="hljs-function"><span class="hljs-title">login</span>(<span class="hljs-params">context,user</span>)</span>&#123; <span class="hljs-comment">//context代表整个vuex对象</span>
      (<span class="hljs-keyword">async</span> <span class="hljs-function"><span class="hljs-keyword">function</span>(<span class="hljs-params"></span>)</span>&#123;
        <span class="hljs-keyword">var</span> result=<span class="hljs-keyword">await</span> axios.get(<span class="hljs-string">&quot;/users/signin&quot;</span>,&#123;
          <span class="hljs-attr">params</span>:user
        &#125;);
        context.commit(<span class="hljs-string">&quot;setUname&quot;</span>,result.data.uname);
      &#125;)()
    &#125;
  &#125;,
  <span class="hljs-attr">modules</span>: &#123;
  &#125;
&#125;)</code></pre></div>

<h3 id="mapState"><a href="#mapState" class="headerlink" title="mapState"></a>mapState</h3><p>当一个组件需要获取多个状态时候，将这些状态都声明为计算属性会有些重复和冗余。为了解决这个问题，我们可以使用 mapState 辅助函数帮助我们生成<span style="color:red">计算属性</span>，让你少按几次键：</p>
<div class="code-wrapper"><pre><code class="hljs html"><span class="hljs-tag">&lt;<span class="hljs-name">template</span>&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">h1</span> <span class="hljs-attr">v-else</span>&gt;</span>Welcome &#123;&#123;uname&#125;&#125;<span class="hljs-tag">&lt;/<span class="hljs-name">h1</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">template</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">script</span>&gt;</span><span class="javascript"></span>
<span class="javascript"><span class="hljs-keyword">import</span> &#123;mapState&#125; <span class="hljs-keyword">from</span> <span class="hljs-string">&quot;vuex&quot;</span></span>
<span class="javascript"><span class="hljs-keyword">export</span> <span class="hljs-keyword">default</span> &#123;</span>
<span class="javascript">  <span class="hljs-attr">computed</span>:&#123;</span>
<span class="javascript">    <span class="hljs-comment">// 使用对象展开运算符将此对象混入到外部对象中</span></span>
<span class="javascript">    ...mapState([<span class="hljs-string">&quot;uname&quot;</span>])</span>
<span class="javascript">  &#125;</span>
<span class="javascript">&#125;</span>
<span class="javascript"></span><span class="hljs-tag">&lt;/<span class="hljs-name">script</span>&gt;</span></code></pre></div>
<h3 id="mapMutation"><a href="#mapMutation" class="headerlink" title="mapMutation"></a>mapMutation</h3><div class="code-wrapper"><pre><code class="hljs html"><span class="hljs-tag">&lt;<span class="hljs-name">template</span>&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">button</span> @<span class="hljs-attr">click</span>=<span class="hljs-string">&quot;logout&quot;</span>&gt;</span>注销<span class="hljs-tag">&lt;/<span class="hljs-name">button</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">template</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">script</span>&gt;</span><span class="javascript"></span>
<span class="javascript">    <span class="hljs-keyword">import</span> &#123;mapMutations&#125; <span class="hljs-keyword">from</span> <span class="hljs-string">&quot;vuex&quot;</span></span>
<span class="javascript"></span>
<span class="javascript">    <span class="hljs-keyword">export</span> <span class="hljs-keyword">default</span> &#123;</span>
<span class="javascript">    <span class="hljs-attr">methods</span>:&#123;</span>
<span class="javascript">        <span class="hljs-function"><span class="hljs-title">logout</span>(<span class="hljs-params"></span>)</span>&#123;</span>
<span class="javascript">            <span class="hljs-built_in">this</span>.setUname(<span class="hljs-string">&quot;&quot;</span>);</span>
<span class="javascript">        &#125;,</span>
<span class="javascript">        <span class="hljs-comment">//和其他方法同级</span></span>
<span class="javascript">        ...mapMutations([<span class="hljs-string">&quot;setUname&quot;</span>])</span>
<span class="javascript">        <span class="hljs-comment">//setUname(uname)&#123; this.$store.commit(&quot;setName&quot;,uanme) &#125;</span></span>
<span class="javascript">    &#125;</span>
<span class="javascript"></span><span class="hljs-tag">&lt;/<span class="hljs-name">script</span>&gt;</span></code></pre></div>
<h3 id="mapActions"><a href="#mapActions" class="headerlink" title="mapActions"></a>mapActions</h3><div class="code-wrapper"><pre><code class="hljs html"><span class="hljs-tag">&lt;<span class="hljs-name">template</span>&gt;</span>
    <span class="hljs-tag">&lt;<span class="hljs-name">div</span> <span class="hljs-attr">class</span>=<span class="hljs-string">&quot;home&quot;</span>&gt;</span>
        用户名:<span class="hljs-tag">&lt;<span class="hljs-name">input</span> <span class="hljs-attr">v-model</span>=<span class="hljs-string">&quot;uname&quot;</span>&gt;</span><span class="hljs-tag">&lt;<span class="hljs-name">br</span>&gt;</span>
        密码:<span class="hljs-tag">&lt;<span class="hljs-name">input</span> <span class="hljs-attr">type</span>=<span class="hljs-string">&quot;password&quot;</span> <span class="hljs-attr">v-model</span>=<span class="hljs-string">&quot;upwd&quot;</span>&gt;</span><span class="hljs-tag">&lt;<span class="hljs-name">br</span>&gt;</span>
        <span class="hljs-tag">&lt;<span class="hljs-name">button</span> @<span class="hljs-attr">click</span>=<span class="hljs-string">&quot;myLogin&quot;</span>&gt;</span>登录<span class="hljs-tag">&lt;/<span class="hljs-name">button</span>&gt;</span>
  <span class="hljs-tag">&lt;/<span class="hljs-name">div</span>&gt;</span>
<span class="hljs-tag">&lt;/<span class="hljs-name">template</span>&gt;</span>
<span class="hljs-tag">&lt;<span class="hljs-name">script</span>&gt;</span><span class="javascript"></span>
<span class="javascript"><span class="hljs-keyword">import</span> &#123;mapActions&#125; <span class="hljs-keyword">from</span> <span class="hljs-string">&quot;vuex&quot;</span></span>
<span class="javascript"></span>
<span class="javascript"><span class="hljs-keyword">export</span> <span class="hljs-keyword">default</span> &#123;</span>
<span class="javascript">  <span class="hljs-attr">name</span>: <span class="hljs-string">&#x27;home&#x27;</span>,</span>
<span class="javascript">  <span class="hljs-function"><span class="hljs-title">data</span>(<span class="hljs-params"></span>)</span>&#123;</span>
<span class="javascript">    <span class="hljs-keyword">return</span> &#123;</span>
<span class="javascript">      <span class="hljs-attr">uname</span>:<span class="hljs-string">&quot;dingding&quot;</span>,</span>
<span class="javascript">      <span class="hljs-attr">upwd</span>:<span class="hljs-string">&quot;123456&quot;</span></span>
<span class="javascript">    &#125;</span>
<span class="javascript">  &#125;,</span>
<span class="javascript">  <span class="hljs-attr">methods</span>:&#123;</span>
<span class="javascript">    <span class="hljs-function"><span class="hljs-title">myLogin</span>(<span class="hljs-params"></span>)</span>&#123;</span>
<span class="javascript">      <span class="hljs-built_in">this</span>.login(&#123;<span class="hljs-comment">//给user</span></span>
<span class="javascript">        <span class="hljs-attr">uname</span>:<span class="hljs-built_in">this</span>.uname,</span>
<span class="javascript">        <span class="hljs-attr">upwd</span>:<span class="hljs-built_in">this</span>.upwd</span>
<span class="javascript">      &#125;);</span>
<span class="javascript">    &#125;,</span>
<span class="javascript">    ...mapActions([<span class="hljs-comment">//去vuex的actions中取出名为login的函数放到此地</span></span>
<span class="javascript">      <span class="hljs-string">&quot;login&quot;</span><span class="hljs-comment">//,&quot;logout&quot;,&quot;registor&quot;</span></span>
<span class="javascript">    ])</span>
<span class="javascript">    <span class="hljs-comment">/**</span></span>
<span class="hljs-comment"><span class="javascript">    原方法:</span></span>
<span class="hljs-comment"><span class="javascript">     * login(user)&#123; </span></span>
<span class="hljs-comment"><span class="javascript">     *  this.$store.dispatch(&quot;login&quot;,user)</span></span>
<span class="hljs-comment"><span class="javascript">     * &#125;,</span></span>
<span class="hljs-comment"><span class="javascript">     */</span></span>
<span class="javascript">  &#125;</span>
<span class="javascript">&#125;</span>
<span class="javascript"></span><span class="hljs-tag">&lt;/<span class="hljs-name">script</span>&gt;</span></code></pre></div>



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